1. Field of the Invention
The present invention relates to a method for the manufacturing of deformation-resistant oxidic protective layers on workpieces.
In an oxidizing atmosphere, many metallic materials will form oxide coatings on their surfaces which can provide a significant protective action against oxidation and corrosion. Moreover, this effect as thermal, diffusion or permeation barrier layers is of important significance.
2. Discussion of the Prior Art
Current samples for the formation of extremely dense, well-covering layers are aluminum, as well as austenitic steels, whose outstanding resistance to corrosion is predicated on such mechanisms.
However, as a rule, oxidic coating layers are brittle so as not to be able to safely sustain appreciable plastic deformations. On the other hand, depending upon the structural make-up and thickness of the layer, they have the capacity to absorb significant elastic stresses. Due to the strong bond, the theoretical tear resistance of the layers is high, and the load capacity of a layer more closely approaches this value the greater the absence of voids. Consequently, mechanically or thermally induced plastic deformations of the base material can be safely sustained without fissures by the layer only to the extent that, taking into consideration the modulus of elasticity of the layer, they correspond to a linearly-elastic stress which is below the practical tear strength. Total deformations which exceed the limit will commence the formation of fissures in the layer.